Mammal Lactation



How do other mammals nurse?

By Dia L. Michels

Reproduced with kind permission.


Days and nights we stayed up in the bracken pile, curled around one another, while I gave suck and licked and settled squabbles. They fed and slept and fed and squabbled, and I watched their small, sleek bodies plumping up with milk. Their eyes were shut, their small heads pushed into my flank, muzzles butting, jaws working hard in the rhythm of life, which is, at first, no more than suck
and swallow.

                 From Fire, Bed & Bone, Henrietta Branford, Candlewick Press, 1998

There are over 4200 species of mammals on our planet. Mammals are animals that have a backbone, have hair or fur, are warm-blooded and whose females nurse their babies with milk. Each of these milks contains water, proteins, fats, carbohydrates, minerals, vitamins, cellular content and anti-infective agents. But each species of mammal produces a milk that is qualitatively different than the milk of other species, a milk that is perfectly suited for the growth and development of the offspring of that particular species.

The composition of the milk is related to the rate of growth of a species. Human milk is low in both protein and fat. Mammals with high fat content generally have young who need to form a thick coat of blubber to protect them from the cold. Mammals with a high protein content generally have young where growth is rapid and the young mature in a short time. Humans are among the slowest growing of all mammals.

Percent Protein and Fat in Milk


% Protein

% Fat




Talapoin monkey









African elephant



Black bear



Little brown bat



Gray seal






Blue whale



House mouse



One important feature of all non-human mammals is that they suckle their young until they are able to become independent. Breastfeeding is the crucial bridge between infancy and maturity. Here’s how some different mammals breastfeed...

The female duck-billed platypus breastfeeds without benefit of a breast or a nipple. The mammary glands rest underneath the mother's chest. The youngster pushes against the chest wall with his soft, pliable bill, then licks the oozing milk off his mother's skin and hair.
Whales need to preserve their sleek, hydrodynamically efficient shape. The mother's milk glands are below her thick blubber layer. This inside location also protects the milk from cold. The baby nudges the area and milk-thick as cream-spurts out. A baby Pacific gray whale can drink 80 pounds of breastmilk a day.
Hippos are born underwater-and nurse underwater, too. The mother puts her head under water and boosts the newborn to the surface to breathe. Then the baby goes under again, finds a nipple and suckles, instinctively folding down his ears and closing his nostrils. Every twenty to forty seconds, he bobs to the surface to breathe and swallow.
Female and young lions live together in a pride. In one pride, all the lionesses take care of all the cubs. Unlike almost all other mammals, any lioness will wet-nurse any cub. A napping lioness who has been huting all night doesn't pay much attention to who is suckling on her. And because they are all so closely related, a lioness helps the family no matter whose baby she nurses.
The hooded seal lives about thirty years, but spends only four days nursing and being a child, the shortest nursing period of any mammal. They live at sea, but they must give birth and nurse out of the water. The only surface available is floating ice. Pups are born when the ice is beginning to melt and break up. A sudden storm might send pieces crashing together, crushing moms and pups. Or an ice floe might split, and moms and pups could be separated. A short childhood helps avoid these perils.
Orangutans breastfeed, ride on their mother's body and sleep in her hest for seven years-among the longest nursing period of any mammal. The young stay with their mothers at least until a new baby arrives; males begin to wander off then, but females may stay around for a while observing how babies are cared for. They are accomplished acrobats, often nursing upside down-hanging by a hand and a foot from a branch.
Baby animals are weaned when the mother is newly pregnant or preparing for another pregnancy. In western culture, today, the most common reason cited for human weaning is in preparation to return to a job outside the home.

Reprinted with permission from Breastfeeding at a Glance, By Dia L. Michels and Cynthia Good Mojab, M.S.with Naomi Bromberg Bar-Yam, Ph.D. Platypus Media, 2001, ISBN: 1-930775-05-9.

Adapted from: If My Mom Were A Platypus: Mammal Babies and their Mothers. By Dia L. Michels, Illustrated by Andrew Barthelmes, Platypus Media, 2005, ISBN: 1-930775-35-0.

This handout is available at:  It may be copied and distributed without permission.  For more information, contact Dia Michels at or visit or call 1-877-PLATYPS (toll-free) or 1-202-546-1674.  




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